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Pollen tube growth is inhibited and promoted by long- and short-chain carboxylic acids, respectively, but is not affected by formic acid. For auxin- and gibberellin-induced elongation of in vitro cultured epicotyl segments of adzuki bean (Vigna angularis), a series of carboxylic acids showed similar effects as that on pollen tube growth except that formic acid showed the strongest promotive effect. The effects of formic acid and GA3 on IAA-induced elongation were additive and both were strongly inhibited by inhibitors of cellulose synthesis (coumarin) and microtubule formation (colchicine). Formic acid, possibly by incorporation into the segments, prolonged the promotion by IAA and GA3 of the elongation of epicotyl segments. Based on these results and later advances in our understanding of metabolism and the role of formic acid in protecting against oxidative stress, a possible role of formic acid on stem elongation is discussed.

Root border cells (RBCs) surround the root apices in most plant species and are involved in the production of root exudates. We tested the relationship between pectin content in root tips and aluminum (Al) tolerance by comparing these parameters in wild-type (WT) and sensitive-to-Al-rhizotoxicity ( star1 ) mutant rice plants. Staining for demethylesterified pectin decreased after Al treatment in the WT. A high level of pectin was observed in RBCs of the root tips. The level of total pectin was increased by about 50% compared with the control. In the Al-sensitive star1 mutant, Al treatment decreased root elongation and pectin content, especially in RBCs. In addition, almost no Al accumulation was observed in the control, whereas more Al was accumulated in the RBCs of STAR1 roots. These results show that the amount of pectin influences Al tolerance; that Al accumulation in rice roots is reduced by the distribution of pectin in root-tip RBCs; and that these reactions occur in the field around the RBCs, including the surrounding mucilage. Al accumulation in rice roots is reduced by the distribution of pectin in root tips, and pectin in the root cell walls contributes to the acquisition of Al tolerance in rice by regulating its distribution. The release of Al-binding mucilage by RBCs could play a role in protecting root tips from Al-induced cellular damage.

When grafting or wounding disconnects stem tissues, new tissues are generated to restore the lost connection. In this study, the molecular mechanism of such healing was elucidated in injured stems of ARABIDOPSIS: Soon after the inflorescence stems were incised, the pith cells started to divide. This process was strongly inhibited by the elimination of cauline leaves, shoot apices, or lateral buds that reduced the indole-3-acetic acid supply. Microarray and quantitative RT-PCR analyses revealed that genes related to cell division, phytohormones, and transcription factors were expressed because of incision. Among them, two plant-specific transcription factor genes, ANAC071 and RAP2.6L, were abundantly expressed. ANAC071 was expressed at 1–3 d after cutting exclusively in the upper region of the cut gap, with concomitant accumulation of indole-3-acetic acid. In contrast, RAP2.6L was expressed at 1 d after cutting exclusively in the lower region, with concomitant deprivation of indole-3-acetic acid. The expression of ANAC071 and RAP2.6L were also promoted by ethylene and jasmonic acid, respectively. In transformants suppressing the function of RAP2.6L or ANAC071, the division of pith cells was inhibited. Furthermore, the ethylene signaling-defective ein2 mutant showed incomplete healing. Hence, plant-specific transcription factors differentially expressed around the cut position were essential for tissue reunion of Arabidopsis wounded flowering stems and were under opposite control by polar-transported auxin, with modification by the ethylene and jasmonic acid wound-inducible hormones.

Laser microdissection (LMD) is used for isolating specific regions or single cells from a wide variety of tissue samples under direct microscopic observation. The LMD method enables the harvest of the cells of interest in a region or specific cells for several analyses, such as DNA/RNA analysis, proteomics, metabolomics, and other molecular analyses. Currently, LMD is used to study various biological events at the tissue or cellular level; it has been used in a wide range of research fields. In this report, we describe techniques for isolating different tissues/specific cells from cryosections of incised Arabidopsis flowering stems by LMD for spatiotemporal quantitative plant hormone analysis. The endogenous indole-3-acetic acid levels in the epidermis/cortex, vascular bundles, and pith of Arabidopsis flowering stems were approximately 19.0 pg mm−3, 33.5 pg mm−3, and 3.32 pg mm−3, respectively, and these endogenous levels were altered spatiotemporally after incision. We also analyzed jasmonic acid from LMD-isolated cells and showed that the endogenous levels increased in the range of approximately 200–3,500 pg mm−3 depending on the tissue and region at 1 h after incision and then decreased to less than 100 pg mm−3 or undetectable levels at 24 h after incision. Quantitative analyses of phytohormones, including jasmonic acid-related molecules, gibberellin, abscisic acid, and cytokinins, could also be performed using the same cell samples. These results showed that spatiotemporal changes in plant hormones could be quantitatively and simultaneously analyzed by LMD-isolated cells from cryosections with positional information. The combination of quantitative analysis by liquid chromatography-mass spectrometry (LC–MS) and sampling by the LMD method provides a comprehensive and quantitative understanding of spatiotemporal changes in plant hormones in a region- and tissue-specific manner. Therefore, LMD-LC–MS methods will contribute to our understanding of the physiological events that control the process of plant growth and development.

Interactions among the functionally specialized organs of higher plants ensure that the plant body develops and functions properly in response to changing environmental conditions. When an incision or grafting procedure interrupts the original organ or tissue connection, cell division is induced and tissue reunion occurs to restore physiological connections. Such activities have long been observed in grafting techniques, which are advantageous not only for agriculture and horticulture but also for basic research. To understand how this healing process is controlled and how this process is initiated and regulated at the molecular level, physiological and molecular analyses of tissue reunion have been performed using incised hypocotyls of cucumber ( Cucumis sativus ) and tomato ( Solanum lycopersicum ) and incised flowering stems of Arabidopsis thaliana . Our results suggest that leaf gibberellin and microelements from the roots are required for tissue reunion in the cortex of the cucumber and tomato incised hypocotyls. In addition, the wound-inducible hormones ethylene and jasmonic acid contribute to the regulation of the tissue reunion process in the upper and lower parts, respectively, of incised Arabidopsis stems. Ethylene and jasmonic acid modulate the expression of ANAC071 and RAP2.6L , respectively, and auxin signaling via ARF6/8 is essential for the expression of these transcription factors. In this report, we discuss recent findings regarding molecular and physiological mechanisms of the graft union and the tissue reunion process in wounded tissues of plants.

ANAC071 and its homolog ANAC096 are plant-specific transcription factors required for the initiation of cell division during wound healing in incised Arabidopsis flowering stems and Arabidopsis hypocotyl grafts; however, the mechanism remains mostly unknown. In this study, we showed that wound-induced cambium formation involved cell proliferation and the promoter activity of TDR/PXY (cambium-related gene) in the incised stem. Prior to the wound-induced cambium formation, both ANAC071 and ANAC096 were expressed at these sites. anac-multiple mutants significantly decreased wound-induced cambium formation in the incised stems and suppressed the conversion from mesophyll cells to cambial cells in an ectopic vascular cell induction culture system (VISUAL). Our results suggest that ANAC071 and ANAC096 are redundantly involved in the process of “cambialization”, the conversion from differentiated cells to cambial cells, and these cambium-like cells proliferate and provide cells in wound tissue during the tissue-reunion process.Matsuoka et al. study the mechanism by which transcription factors ANAC071 and ANAC096 promotes regeneration of wounded tissue in Arabidopsis by mutagenesis and morphological characterization. They find that these factors are essential for wound-induced cambium formation from dedifferentiated cells before the initiation of cell division.

Patients with type 2 diabetes who have cardiovascular disease and are receiving empagliflozin have a lower rate of primary composite cardiovascular outcomes. In contrast, glimepiride increases cardiovascular hospitalization when combined with metformin. Here, we assessed the effects of empagliflozin and glimepiride on endothelial function using flow-mediated dilation (FMD). In this prospective, open-label, randomized, parallel-group study, 63 patients with type 2 diabetes received metformin and insulin glargine U100 for 12 weeks. This was followed by additional treatment with empagliflozin or glimepiride for 12 weeks. The primary outcome was the change in the FMD measurement (ΔFMDs) at 24 weeks of additional treatment. Secondary outcomes comprised changes in metabolic markers and body composition. The empagliflozin group ( n = 33) and glimepiride group ( n = 30) showed no significant differences in ΔFMDs (empagliflozin, −0.11 [95%CI: -1.02, 0.80]%; glimepiride, −0.34 [95%CI: -1.28, 0.60]%; P = 0.73). Additionally, changes in glycated hemoglobin were similar between the two groups. However, a significant difference in body weight change was observed (empagliflozin, −0.58 [95%CI: -1.60, 0.43] kg; glimepiride, 1.20 [95%CI: 0.15, 2.26] kg; P = 0.02). Moreover, a body composition analysis revealed that body fluid volume significantly decreased after empagliflozin treatment (baseline, 35.8 ± 6.8 L; after 12 weeks, −0.33 ± 0.72 L; P = 0.03). Hence, although empagliflozin did not improve endothelial function compared with glimepiride for patients with type 2 diabetes, it did decrease body fluid volumes. Thus, the coronary-protective effect of empagliflozin is not derived from endothelial function protection, but rather from heart failure risk reduction. Trial registration: This trial was registered on September 13, 2016; UMIN000024001 .

The tapetum plays important roles in anther development by providing materials for pollen-wall formation and nutrients for pollen development. Here, we report the characterization of a male-sterile mutant of glycine-rich protein 2 (OsGRP2), which exhibits irregular cell division and dysfunction of the tapetum. GRP is a cellwall structural protein present in the cell walls of diverse plant species, but its function is unclear in pollen development. We found that few GRP genes are expressed in rice and thus focused on one highly expressed gene, OsGRP2. The tapetal cell walls of an OsGRP2 mutant did not thicken at the pollen mothercell stage, as a result, pollen maturation and fertility rate decreased. High OsGRP2 expression was detected in male-floral organs, and OsGRP2 was distributed in the tapetum. OsGRP2 participated in establishment of the cellwall network during early tapetum development. In conclusion, our results indicate that OsGRP2 plays important roles in the differentiation and function of the tapetum.

Aims This randomized, open-label, parallel-group, controlled trial compared the effects of dulaglutide and trelagliptin on beta-cell function in patients with type 2 diabetes. Materials and methods For 24 weeks, participants received dulaglutide (0.75 mg/week) or trelagliptin (100 mg/week), after which beta-cell function was evaluated using a glucagon stimulation test-based disposition index. The primary endpoint was the change in disposition index over the 24-week treatment period. Results Fifty patients with type 2 diabetes who received metformin with or without basal insulin were randomized to receive dulaglutide or trelagliptin. Forty-eight patients completed the 24-week dulaglutide ( n  = 23) or trelagliptin ( n  = 25) treatment. The dulaglutide group reduced HbA1c levels more than the trelagliptin group (dulaglutide: − 0.77% ± 0.07% vs. trelagliptin: − 0.57% ± 0.07%; p  = 0.04). Change in disposition index during the 24 weeks did not differ between the groups (dulaglutide: − 0.07 ± 1.08 vs. trelagliptin: + 0.59 ± 1.04; p  = 0.66), but the dulaglutide group increased HOMA2-%β levels more than the trelagliptin group (dulaglutide: + 26.2 ± 4.3% vs. trelagliptin: + 5.4 ± 4.1%; p  = 0.001). The dulaglutide group showed greater body fat mass reduction than the trelagliptin group (dulaglutide: − 1.2 ± 0.3 kg vs. trelagliptin: − 0.3 ± 0.2 kg; p  = 0.02) without skeletal muscle mass loss. Conclusion Dulaglutide and trelagliptin had similar effects on beta-cell function according to the glucagon stimulation test-based disposition index. However, dulaglutide promoted improved HOMA2-%β levels compared to trelagliptin and body fat mass was reduced without loss of skeletal muscle mass (UMIN-CTR 000024164).

Cellulosic biomass is available for the production of biofuel, with saccharification of the cell wall being a key process. We investigated whether alteration of arabinoxylan, a major hemicellulose in monocots, causes an increase in saccharification efficiency. Arabinoxylans have β-1,4-D-xylopyranosyl backbones and 1,3- or 1,4-α-l-arabinofuranosyl residues linked to O-2 and/or O-3 of xylopyranosyl residues as side chains. Arabinose side chains interrupt the hydrogen bond between arabinoxylan and cellulose and carry an ester-linked feruloyl substituent. Arabinose side chains are the base point for diferuloyl cross-links and lignification. We analyzed rice plants overexpressing arabinofuranosidase (ARAF) to study the role of arabinose residues in the cell wall and their effects on saccharification. Arabinose content in the cell wall of transgenic rice plants overexpressing individual ARAF full-length cDNA (OsARAF1-FOX and OsARAF3-FOX) decreased 25% and 20% compared to the control and the amount of glucose increased by 28.2% and 34.2%, respectively. We studied modifications of cell wall polysaccharides at the cellular level by comparing histochemical cellulose staining patterns and immunolocalization patterns using antibodies raised against α-(1,5)-linked l-Ara (LM6) and β-(1,4)-linked d-Xyl (LM10 and LM11) residues. However, they showed no visible phenotype. Our results suggest that the balance between arabinoxylan and cellulose might maintain the cell wall network. Moreover, ARAF overexpression in rice effectively leads to an increase in cellulose accumulation and saccharification efficiency, which can be used to produce bioethanol.